Tree peonies (paeonia suffruiticosa) are shrubs with both Chinese and Japanese cultivars. They have large pink, red and yellow flowers, with beautiful names like Green Dragon Lying and Godaishu. Tree peonies are slow growing, taking years to get up to 5 feet, but they can live for hundreds of years. Tree peonies do well in hardiness zones 4 through 9, and they should be planted in an area with well-drained soil.that is partially shielded from strong winds. They also enjoy plenty of sunshine and acidic soil (above 6.0 pH). You should plant tree peonies 4 to 5 feet apart.
Dig a whole deeper and wider than 2 feet, depending on the size of the root stock. Ideally, the point at which the rootstock and the stem meet should be at least 5 inches underground. Fill in the bottom foot of the whole with loam soil mixed with 1-1/2 cups of bone meal.
Place the tree peony root system in the hole. Make sure that the root sprouts are turned up. Fill the rest of the hole with top soil, being sure to cover all of the roots.
Water the tree peony so that the soil is very damp, but not standing in water. It is best to water tree peonies deeply during the dry months rather than adding shallow amounts of water more often. Add mulch before the ground freezes to protect the young tree. Straw and sawdust are good choices to mound up. Remove the mulch when spring arrives.
Fertilize after three years. Tree peonies don't need to be fertilized sooner as long as the soil retains a pH level above 6.0. If you are uncertain, test a soil sample to make sure the nutrients have not been washed away by rain or overwatering. If the pH is under 6.0, add the proper nutrients to raise the level to over 6.0.